Lepchenko, ranked 63rd in the world, beat the 2010 winner and 2011 runner-up 3-6 6-3 8-6 in a match full of long rallies in the midday sun on Court One, where the temperature reached 29 degrees Celsius.

Italian Schiavone, the 14th seed, lost in the first round to the Uzbekistan-born Lepchenko on Madrid's blue clay last month, and said before Saturday's game that she found playing left-handers troublesome.

After three exchanges of break in the third set, Lepchenko broke again to go 7-6 up and then saved four break points before smashing a winner on match point to finish off the victory in three hours and two minutes

Lepchenko, who will now play fourth-seeded Czech Petra Kvitova, said she had found Schiavone a completely different opponent from the woman she beat in Spain.

"In Madrid she was missing so much and making easy errors, and here she started out amazing," Lepchenko told a news conference. "I was like, 'oh, now I know why she won a grand slam'. She was playing unbelievable.

"I had to really pull it together and stay very aggressive and fight," Lepchenko added. "Till the very end, I didn't know if I was going to win, but I kept believing in myself.

"I kept thinking, okay, this is... going to be over soon for me, but something deep inside of me still was like, 'no, you can do it, you can do it'. I'm so happy to be through."

Schiavone was happy, too, with the improvement in her own game but chided herself, saying: "I had my chances, I simply didn't take them."